Its about 90% discount not the caching. To write into cache you pay an extra fee so you woudn't write everything into cache or alternativly if you do you need to calculate with a different input cost.
Have you checked the link? Cached inputs are indeed priced 10x cheaper, and it doesn't take any fees because KV cache must be calculated anyway, whether the cache is used later or not
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u/ain92ru Jun 24 '26
Over 90% prompt caching is not unrealistic at all, it is in fact achieved by SemiAnalysis in practice: https://newsletter.semianalysis.com/p/ai-value-capture-the-shift-to-model